Portrayal in adaptations

Wargs are taller and darker than regular wolves, but due to the progression in the game, pose less of a threat; whereas wolves are only encountered by a stick-wielding Frodo, wargs appear only in levels in which the player is Gandalf or Aragorn.

Wargs appear to be more like a "hyena-bear-wolf hybrid" rather than wolves, in an effort to distinguish them from regular wolves by presenting them as some sort of distant cousin. However, it should be noted that Tolkien never actually described Wargs beyond stating they were demonic wolves.